Description from Flora of China
Carex nikoensis Franchet & Savatier; C. satsumensis var. longiculma Hayata; C. satsumensis var. nakaii Hayata.
Rhizome elongate and creeping. Culms loosely tufted, triangular, 7-20 × ca. 0.15 cm, glabrous, striate. Leaves shorter or longer than culms, flat, 1.5-7 mm wide, slightly stiff, glabrous; basal leaf sheaths blackish brown, fibriform. Involucral bracts linear, shorter than inflorescence, without sheaths. Inflorescence spicate, terminal, oblong-cylindric, 3-8 × 1-1.7 cm. Spikes numerous, androgynous, dense and patent, oblong, arising from cladoprophylls with a developed female flower inside, several basal ones sometimes branched; male part of spikelet tiny, 2-3 mm, with 4 or 5 flowers; female part with numerous and dense flowers; male glumes pale yellow or pale brown, lanceolate, 2.5-3 mm, membranous, apex acuminate; female glumes pale yellow or pale brown laterally, ovate, 2-2.5 mm, membranous, with 1 midrib, margins hyaline, apex acute. Utricles pale yellow-brown at maturity, patent, slightly longer than glumes, oblong-lanceolate, bluntly trigonous, 2.5-3 mm, membranous, with 2 raised lateral veins and several fine veins abaxially, nerveless and paler adaxially, base contracted abruptly into a short stipe, apex attenuate into a long beak, orifice obliquely truncate. Nutlet pale yellow at maturity, oblong, bluntly trigonous, ca. 1.5 mm, base attenuate, apex not apiculate; style base slightly thickened; stigmas 3.
Sandy places. Taiwan [Japan, Philippines, Vietnam].